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Ketones with two available α-methylene positions react more quickly at the least hindered position.: [1] Allylic oxidation can be predicted by the substitution pattern on the olefin. In the case of 1,2-disubstituted olefins, reaction rates follow CH > CH 2 > CH 3: Geminally-substituted olefins react in the same order of reaction rates as above ...
Selones (R 2 C=Se) are the selenium analogues of ketones. They are rare due to their tendency to oligomerize. [11] Diselenobenzoquinone is stable as a metal complex. [12] Selenourea is an example of a stable compound containing a (formal) C=Se bond. Thioselenides (R−Se−S−R), compounds with selenium(II)–sulfur(II) bonds, analogous to ...
Selenium is found in metal sulfide ores, where it substitutes for sulfur. Commercially, selenium is produced as a byproduct in the refining of these ores. Minerals that are pure selenide or selenate compounds are rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells.
Sample of cadmium selenide, a pigment. The parent inorganic selenide is hydrogen selenide (H 2 Se). It is a colorless, malodorous, toxic gas. It dissolves in aqueous solution, to give the hydrogenselenide or biselenide ion HSe −. At higher pH, selenide forms. Solutions of hydrogen selenide and selenide are oxidized by air to give elemental ...
Selenium Remote Control was a refactoring of Driven Selenium or Selenium B designed by Paul Hammant, credited with Jason as co-creator of Selenium. The original version directly launched a process for the browser in question, from the test language of Java, .NET, Python or Ruby.
Selenium dioxide is the chemical compound with the formula SeO 2. This colorless solid is one of the most frequently encountered compounds of selenium . It is used in making specialized glasses as well as a reagent in organic chemistry.
In the selenium cycle it has been found that bacteria, fungi, and plants, especially species of Astragalus, metabolize the most oxidized forms of selenium, selenate or selenite, to selenide. It is also thought that microorganisms may be able to oxidize selenium of valence zero to selenium of valence +6.
The original synthesis involved the redistribution reaction of selenium dioxide and selenium tetrachloride. Pure selenium oxydichloride autoionizes to a dimer: [4] SeOCl 2 ↔ (SeO) 2 Cl + 3 + Cl −. The SeOCl 2 is generally a labile Lewis acid and solutions of sulfur trioxide in SeOCl 2 likely form [SeOCl] + [SO 3 Cl] − the same way. [5]